1. Field of the Invention
The present invention generally relates to systems of authentication of an integrated circuit supported by a distant element (for example, an electronic tag to be placed on any product). The present invention more specifically relates to systems which require, for an authentication, three distinct elements, that is, the integrated circuit to be authenticated, a reader of information contained in the circuit, and a host communicating with the reader.
2. Discussion of the Related Art
An example of application of the present invention concerns the marking by radiofrequency tag of distribution system consumables. For example, these may be “coffee machine” refills or printer cartridges. The authentication is then used to guarantee that only cartridges authorized by the manufacturer are used by a given printer. In such an application, the integrated circuit to be authenticated is supported by the printer cartridge in the form of an electronic tag capable of communicating, in a contactless and wireless manner, with a reader, such as an electromagnetic transponder. The reader is connected to the host by means of a connection of another type, for example, an electric interface of type I2C or the like.
“Application” will be used hereafter to designate all the tasks performed by the system (for example, the printer) once the tag has been authenticated.
For the application to operate properly, the electronic tag must previously have been authenticated to make sure that the product (for example, a cartridge or a refill) which supports it is an authorized product (for example, to make sure that the merchandise marked by the tag has not been replaced by an imitation).
The function of the host (formed, for example, of a microcontroller, of a distant computer or of any other adapted electronic system) is to control the application, that is, the authentication program as well as the appropriate actions following the detection (for example, blocking of the printer or of the coffee machine in a no-authentication case). In these fields, the host will preferentially be a microcontroller equipping the automatic vending machine or the printer. It may however also be a distant host communicating, for example, by telephone connection or by dedicated line, with different readers.
The communication between the host and the reader is based on accessible widespread protocols to enable use of different readers with the same host equipped with the application controller. However, this generates a weakness in terms of security, especially if the host is distant from the reader (even slightly, while being in the same device). The final tag authentication decision to allow correct execution of the application belongs to the host.
Known authentication systems use cryptography algorithms to authenticate an electronic tag based on a specific secret key. For example, algorithms of DES type (Data Encryption Standard) are used.
A disadvantage of such cryptography algorithms is that they require an electronic tag provided with high-performance calculation means, in the case in point, generally a microprocessor. The cost generated by such calculation means makes these systems poorly adapted to refills or goods of consumable type for which the cost of the electronic tag is desired to be minimized due to the fact that said tag is short-lived.